Method for metal coating



March 24. 1925.

H. W. PLEISTER METHOD For: METAL comme Filed Dec. 29. 1923 Patented Mar.24, 1925.

UNITED STATES PATENT OFFICE.

HENRY W. PLEISTER, F WESTFIELD, NEW JERSEY, ASSIGNORQBY MESNE ASSIGN-llflENTS,v TO DIAMOND EXPANSION BOLT COMPANY, 0F NEW' YORK, N. Y., ACOR- PORATION 0F NEW YORK.

METHOD ron METAL coATING.

Application filed December 29, 1923. v Serial No. 683,424.

T0 all 'whom it may concern vBe it known that I, HENRY IN. PLEISTER, acitizen of the United States, and resident of Westfield, in the countyof Union and State-of New Jersey, have invented certain new and usefulImprovements in Methods for Metal Coating, of which the following is aspecification.

This invention relates to the method of coating iron or steel articleswith zinc applied in a molten state and allowed to cool and hardenthereon, the process commonly known as galvanizing. Y

This invention relates more particularly to the process of distributingthe liquid or semi-liquid coating of zinc while still in a molten stateon the surface of the articles so as to form a smooth and even coatingof equal density on all surfaces of an irregularly shaped article.

Another object of this invention is to prevent the articles remaining inclose contact one with the other when handled in a mass in order toprevent their sticking or freezing one to the other.

It is customary in the process of galvanizing after an article or a massof articles have been properly pickled to immerse the article separatelyor a mass of articles in perforated baskets into a bath of molten zincapproximately 50 degrees to 100 degrees Fahrenheit above the meltingpoint of the zinc and to allow the articles to remain until raised to atemperature equal approximately `to the heat of the molten zinc; thearticles are then subjected to various treatments after they are takenout of the bath according to the different processes employed by variousgalvanizers such for instance `as shaking the basket vigorously by handand throwing the contents on 'the door to spread the articles and toprevent stickers, wiping the surface to spread the coating smoothly andto remove excess spelter or subjecting the mass to rotation so thattheexcess spelter is thrown olf by centrifugal force.

The objectionable features to al] of'these n processes are numerous, thecost of wiping threads on bolts is excessive and the result does notbrin about a smooth and uniform `ob.- 4'Such bo ts often require thethreads to ere-cut with a die in order to permit the nuts being turnedonthe bolts The shaking in perforated baskets by hand is excessivelylaborious and the production per man is very low. Submitting thearticles to simple centrifugal motion has its disadvantages in that themass thus rotated retains its original relative position one article tothc other in the centrifugal chamber. Thus articles for instance whichhappen to be at the center of the centrifuge will continuev there toremain and to cast excess spelter on the articles nearer the peripherywhich excess spelter often freezes on the articles at the outside orperiphery causing blisters, icicles, roughness and excess spelter.Articles treated in this manner retaining their same relative positionone to the other will in many cases freeze or stick together when'thezinc cools and hardens and when broken apart will leave bare or exposedspots'on one or the other. When a simple centrifuge is used the articleswill be coated more thickly on the side further removed from the centerthan on the side nearer'to the center. This is for the reason that thearticle retains its original position and the centrifugal force willdraw the fluid spelter outwardly taking it from the side nearer thecenter and drawing it to the side further away causing an unevendistribution of the zinc when hardened. Another objection to the simplecentrifuge is that in a mass of articles the articles nearer or at theperiphery are subject to more violent action than those nearer to .or atthe center where practically no action occurs. This it will be readilyseen causes differentv densities of coating to be left on the articles.With sufficient speed it is possible practically to cast olf all thespelter from the outer articles while those at the center 0f rotationstill retain a very thick coating.

In my process of galvanizing I employ a primary horizontal rotaryplatform upon which is mounted between its center and circumference asecondary rotating platform. Upon this is mounted suitable supports forretaining a perforated basket. A planetary 'rotation of the secondaryrotating platform is obtained by means of a xed pinion at the center ofthe primary rotating platform which pinion meshes in the teeth of a gearmounted underneath the secondary platform on its center. Thus when theprimary platform S IOtated' the pinion being fixed I against rotationthe secondary platform will scribed and claimed as new hereafter. In

` ary rotatable.

order to make this application entirely clear I will describe it inconnection with the particular preferred apparatus thatis shown in thedrawings.

-It is further understood that the speed of revolution of the secondarycentrifuge 'may be varied in relation to the primary to any degree thatis found more eiiicient for certain classes of work. While in themajority of cases the relation of threerevolutions to the primaryrotating platform to one revolution of the secondary rotating platformis found to be most satisfactory this relation may easily be changed bythe substitution of different sizes of gears-and pinions. For ease ofdescription I will in Vthe accompanying drawings and followingdescription illustrate and describe theaction of the apparatus soconstructed as to give one revolution on the primary to one revolutionon the secondary rotating platform.

Figure 1 is a cross sectional elevation of the preferred form of myapparatus; and

Flgure 2 is a horizontal view of same,

looking down upon the rotatable platforms;

Figures 3, 4, 5, and 6 are diagrammatic plan views of the rotatableplatforms in different positions takenv at each quarter turn, eachplatform rotating clockwise; and

Figs. 7 and 8 are diagrammatic plans showing orbits of an article; withdifferent ratios between rthe rotation of the primary andsecondarytables. y

In Figures land 2 ais a stationary pinion mounted rigidly on a fixedshaft. b supported on a base c; the primary rotatable platform alv isloosely fitted to the shaft or column b. Thisv rotatable table may beactuated by a belt about the pulley e or by shaft and gear or in anyother suitable manner. A secondlatfo'rm f is mounted on a shaft g spacedetween' the center of the primary table and its circumference and fixedrigidly agearwheel la." which meshes with thev p1n1on a. On theysecondary rotatable platform f is suitably mounted a perforated basketjsupported by upright c'. AWhen the primary platform d is rotated thesecondary platform will travel with it about the center of the column Zat the same .time rotating about' its own cente This apparatus ispreferably enclosed in a steel or other'suit-y able shield Z tovrevent'the spelterwhich is as it is placed in the basket cast ofiI thecoated article from ying about the room andV to allow it to fall to thebottom of the enclosure where it may be removed and replaced in themolten bath for repeated use.

In my process of galvanizing articles to be coated are first cleaned orpickled in the usual manner in diluted sulphuric, hydroiiuoric ormuriatic acid, according tothe class of work,^diferent acids being usedfor bright cold rolled steel, rough hot rolledu steel, cast iron, etc.After being pickled they are immersed in a bath of molten zinc atapproximately 850 to 900 degrees Fahrenheit larger articles beinglimmersed separately or strung on wires, smaller. articles beingimmersed in a mass in aA perforated steel basket. The articles areallowed topremain in the zinc bath until they have attainedapproximately the temperature of the bath throughout. They are thentaken from the bath and placed upon the secondary rotary table f of myapparatus and subjected while the zinc coating is still in a liquid orsemiliquid state on the surface of the articles to a' compound rotarymotion suiiciently long to expel all surplus zinc and evenly todistribute the coating of molten zinc smoothly and of equal densityover'the entire surface of the articles. Very few revolutions of theapparatus are necessary to accomplish this and the material is thenremoved from the apparatus. If small articles are-treated in bulk in aperforated basket the basket is taken from the machine and dumped uponan inclined chute, while sliding 'down this chute they are sprinkledwith salammoniac and allowed .to fall into a tank of clear cold water.This process results in a smooth 'bright coating of zinc upon the steelor iron articles with uniform thicknesson all surfaces free from lumps,projections, blisters or any kind of roughness. `Where threaded articlesare so coated the threads of a4 bolt `are clear and free in the 'threadsand in thev slot vof thehead so that no'further cleaning or machine workis necessary on the-m and a uut may be run freely over the threads ofthe bolts.

The even distribution of the metal on 'the llO articles is accomplishedbythe particular' rotary motion which is applied in my appaures 34, 5, 6and 7. In Figure 3, Ihave shown as exemplary of many other shapes anarticle M having at leastA four O, P, placed in a perforatedl basketupon the secondary rotating platform f. .Its position in `the basket isone of any number of positions that it may have when the basket isremoved from the molten zinc and is o ne of many similar articles withwhich the basket lis filled though not shown in the drawing.

approximately I Its position will be retained due -to its con sides' N,R,

ratus and which motion is illustrated in Figtact with the surroundingarticles which lill the basket. In Figure 3 and each of the succeedingFiguresft, 5, and 6, the lines of centrifugal force radiate from thecenter X of the primary rotatable table and are marked LCF. When theprimary rotatable table is turned clockwise the secondary table willalso turn clockwise and in an orbit around the center'X. When in theposition shown in Figure 3 the-lines of centrifugal force will draw theliquid metal from the side P to the side R. When the primary rotatabletable has made a quarter turn on its center Figure 4, the secondaryrotatable-table will have made a quarter turn on its center also, andthe article M will take the position shown in Figure 4 and the lines ofcentrifugal yforce are from the sides O and P toward the sides R and N.When the next quarter turn has' been made Figure 5, the article M hastaken the position shown in the drawing and the lines of centrifugalforce are from the side R toward the side P. When the next quarter turnhas been taken the article M is in the position shown -in Figure 6 andthe lines of centrifugal force are from the sides N and P toward thesides R and O.. IVhen the next ,quarter turn has been taken the articleM will have again taken the positionA shown in Figure 3, the originalposition at which it started, andthe lines of centrifugal force will befrom the side P to the side R. Thus it willbe seen that the centrifugalaction upon the article M is constantly changing in its directioncausing the metal to be drawn on its surf faces in ever changingdirections assuring the casting off of surplus metal from every angle onthe surface and assuring a smooth and uniform distribution of the fluidmetal over the entire surface of the article.

From the above description it can readily be seen that the ever changingdirection of the lines of centrifugal force upon the article treatedproduces an entirely different action from that obtained in the simplecentrifuge where the direction of the lines of centrifugal force remainconstant at all times on each article and where kthe articles at theinner portion of the centrifuge are continually expelling metal uponthose located at the outer portion or nearer to the periphery of thecentrifuge. In my process the article treated is not allowed to remainat the same distance from the center at any time but is constantlychanging its location from the center of the primary rotatable table. InFigure 3, the article M is shown at its extreme distance from the centerX.v In Figure 4 it is Shown at a pointbetween the extreme and theminidistance from the center X. In Fig ure 5 it is shownat its minimumdistance from the center X. In Figure 6 it is again shown at a. pointbetween the extreme and the minimum distance from the center Xand'trifugal action while those at or adjacent 'Figure 8, I have shown theorbit of the article M about the center X where the primary table makesthree revolutions to one revolution of the secondary table. As statedbefore in this description where a` simple centrifuge/.is used certainarticles at or adjacent to the center receive little or no cento thecircumference are more forcibly affected by the centrifugal action; Withmy process all articles receive practically equal cen-A trifugaltreatment in their passage from maximum to minimum ydistance from thecenter.

While I have stated above the articles will be held7 in the samerelative position one to the other during the process of expelling theexcess spelter during their treatment in my apparatus, there is stillsuiicient agitation among the articles caused by the changes in linesVof centrifugal force exerted upon them to prevent their adhering one tothe other so that when the rotation has been completed and the articlesare dumped from the basket down the inclined chute into the water theywill be comparatively free from stickers, the term usually applied togalvanized articles which adhere one to the other.

Articles M disposed over the teeth the Wheel h. will vary in speedsubstantially from zero speed to high speed. JArticles nearer the axisofthe wheel l1. will vary in speed less.

It is further be understood that While l have shown boththeprimary andsecondary rotatable tables operated in a clockwise direction I In. yobtain a similar result by rotating onein a clockwise and the otherin ucounterclockwise direction by the insertion of another gear wheel or inother Ways. It is particularly noted that the invention is not limitedto the details and metal described. as these may be greatly variedwithout '.departing from the yscope of the invention as claimed.

I claim as my invention:

1. A process comprising applying molten metal to an article; lthensubjecting the article to motion in 'an endless deeply 120 curved path;and at the same time varying the relation of the article with respect tothe path. l

2. A process comprising applying molten metal to articles; thensubjecting the articles ,to motion in an endless deeply curved path;

and at the same time Varying the speed of the articles.

3. A process comprising applying molten metal to articles; thensubjecting the articles l less deeply to motion in an endless deeplycurved path at sufficient speed to throw metal from the articles; and atthe same time varying the speed of the articles. v

4. A process comprising applying molten metal to articles; thensubjecting the articles to motion in an endless deeply curved path; andat the Sametime varying the'curvature of the path. j

5. A process comprising applying molten metal to articles; thensubjecting the articles to cyclic motion in a curved path; and at thesame time varying the relation 'of the articles with respect to thepath.

6. A process comprising applying molten metal to articles; thensubjecting the articles to cyclic motion -in a curved path; and at thesame time varying the speed of the articles.

7. A. process comprising applying molten metal to articles; thensubjecting the articles to cyclic motion in a curved path; and at thehsame timevarying'the curvature of the pat v 8. A process comprisingapplying molten metal to articles; then subjecting the articles tocyclic motion in a curvedl path; and at the same time varying the angleof the articles with respect' to the path.

9. A process comprlsmg applying molten` metal to an article; thensubjecting the article to planetary motion.

10. A process comprising applying molten subjecting the article tocentrifugal force; and at the same time varying the relation of theforce with v respect to the article. Y

11. A process comprising applying molten metal to articles; thensubjecting the articles tocentrifugal force; and at thevsame. timevarying the angle of the force with respect to the articles.

l2. A process comprisingapplying molten metal to articles; thensubjecting the articles to cyclic centrifugal force; and at the sametime varying the angle .of the force with respect to the articles.

' 13. A process comprising applying molten meta-l to articles then'subjecting the article/s to cyclic centrifugal force; and at the sametime varying the relation of the force with respect to'the articles. i

14.- A processcomprising applying molten metal to an article; thensubjecting a carrier with the arti-cle therein to motion i`n .anendcurved path; and at the same time varying the angle of the carrierlwith respect to the path. j .l

15. A process comprisin applying molten metal to a-rticles; hensujecting a carrier with articles therein to motion in an -endlessldeeply curved path; andat the. same time positively varyingthe angle ofthecarrier with respect to thel path.

16. The process of galvanizing which constate on the surface of thearticles to sists inA 'immersing the articlesin molten zinc, then removithem to a rotary motion while theA zinc is stillin afliquid orsemi-liquid state on the surface of the articles inl which motion thearticles are rotated centrifugally in constantly chan 'ng distancesfromthe center of the centriiige A 17. The process of galvanizing 'whichconsists in' immersing the articles in molten zinc, `then removing themand subjecting them to a rotary motion while the zinc is still in aliquid or semi-liquid state on the surface of the articles in whichmotion the articles are rotated centrifugallly in constantly changingdistances from the center of the centrifuge whereby each article is'subjected to the-same amount of centrifugal force as the others.

18. The process of galvanizing which consists in zinc, then removingthem and subjecting them to a rotary motion while the zinc is still in ali uid or semi-liquid state on the surface of t e articles in whichmotion the articles are constantly and alternately drawn toward thecenter and away from the center of the centrifuge.

19. Thev process of galvanizing metal articles consisting of immersingthem. in a bath of molten zinc until the temperature of the articles hasbeen brought up to approximately the temperature of the Yzinc, thensubjecting the articles in a mass while the zinc is still in a liquidorvsemi-liquid wa compound rotary motion in which motion the position ofthe articles in relation to the lines of centrifugal force iscontinuously changed.

20.' The process of galvanizing'metal articles consisting of immersingthem in a bath of molten zinc until the temperature of the articles hasbeen brought up to approxi; mately the temperature of the lzinc, thensubjecting the articles in a mass while the zinc is still in a liquid orsemi-liquid state on the. surface of the articles to a compound rotarymotion in which motion the'position of the'articles in relation to thelines of centrifugal force is whereby thev liquid coating will be causedto flow in ever changing directions on the surface of the article. A

21. The process ofA galvanizing metal arlticls consisting of immersingthem vin aat the articles has been brought up to approximately thetemperature of the zinc, then subjecting the articles in. a mass Whilethe zinc surface ofthearticles to a compound rotary motion in whichmotion-the position ofthe articlesin relation to fthe lines of'centrifu- -continuously lchanged g'them .and subjecting immersing thearticles in molten of molten zinc until the temperature of v.is still ina liquid or semi-liquid state on the CTI the excess spelter Will be castotll in ever changing directions relative to the position of thearticle.

22. The process of galvanizing metal articles consisting of immersingthem in a bath of molten zinc until the temperature of the articles hasbeen brought up to approximately the temperature of the zinc, thensubjecting the articles in a mass While still at approximately thesametemperature and While the zinc is still in a liquid or semiliquid stateon the surface of the articles to a compound rotary motion in whichmotion the radial position of the articles in relation each to the otheris continually changed.

23. The process of galvanizing metal articles consisting of immersingthem in a bath of molten zinc until the temperature of the articles hasbeen brought up to approximately the temperature of the zinc, thensubjecting the articles in a mass While still at approximately the sametemperature and While the zinc is still in a liquid or semiliquid stateon the surface of the articles to a compound rotary motion in whichmotion the distance of each article from the center from periphery tocenterand from center ato periphery passing through all pointsinrermediate thereto.

24. The process of galvanizing metal articles consisting of immersingthem in a bath of molten zinc until the temperature of the articles Ahasbeen brought up to approximately the temperature of the zinc, thensubjecting the articles in a mass While still at approximately the sametemperature and while the zinc is still in a liquid or semiliquid stateon the surface of the articles to a compound rotary motion in Whichmotion the distance of each article from the center of the centrifuge iscontinually changed from `periphery to center and from center toperiphery passing through all points intermediate thereto, Whereby noarticle Will be allowed to remain at the circumference to receive thecast olf Spelter from articles nearer the center thereby insuringarticles which are initially placed at the circumference-receiving thesame treatment as those initially placed at or nearer the center.

Signed at New York, in the county of New York and State of New Yorlc,this 26th day of Dec., A. D. 1923.

HENRY W. PLEISTER.

